Electron discharge device



Sept. 21, 1943. w. A. zALEsAK 2,329,780

ELEGTRN DISCHARGE DEVICE Filed oct. 30, 1941 INVENTOR 'Wezglyhmzzzw ATTORNEY Patented Sept. 2l, 1943 UNITED. STATES PATENT OFFICE ELEc'raoN DISCHARGE nEvTcE William A; Zalesak, Townley, N. J., assg'nor to Radio Corporation of America, a corporation of Delaware Application October 30, 1941,- Serial No. 417,061

(Cl. Z50-27.5)

14 Claims.

My invention relates to electron discharge devices, more particularly to such devices useful at high frequencies.

There has recently been developed what has `been termed velocity modulation. for use at ltra high frequencies. In the arrangements proposed the electrons of the electron beam or stream are given varying velocities, the variation oi velocity being applied cyclically so that the beam comprises slow and fast electrons. The fast and slow electrons are permitted to move through a field free space in which the fast electrons overtake the slow electrons; thus producing concentrated groups of electrons or bunching.

, At this point of bunching it is possible to extract period of time of absorption of energy the more intense will be the pulse of energy which can be abstracted from the grouped electrons, or the greater the amplitude of the output Voltage.

It is, therefore, a principal object oi' my invention to provide an improved form of electron discharge device useful at ultra high frequencies and particularly such a tube depending upon cyclically varying the velocity of the electrons in the electron stream.

It is another object of my invention to provide such a tube in which the need for a drift space to bring about grouping of the electrons is eliminated.

A still further object of my invention is to provide such an electron discharge device in which the amplitude or intensity of the pulse of output voltage or current may be increased by decreasing the absorption time of output energy.

More specifically it is an object of my invention to provide an electrode absorption system so formed that energy may be simultaneously extracted from the slow and fast electrons, resulting from the cyclic variation of velocity without the necessity of producing bunching.

The novel features which I believe tobe characteristic of my inventionV are set forth with particularlty in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which the single figure in the drawing is a schematic longitudinal section of an electron discharge device made according to my invention.

In accordance with my invention an electron discharge device is provided with an elongated evacuated envelope I 0 having at one end the cathode II heated by the heater'IZ and surrounded by a grid electrode I3 extending transversely of the envelope and provided with a tubular collar I4 closely adjacent the tube wall of the envelope. Positioned at the other end of the envelope is a collector electrode in the form of a drum I5 extending transversely of the envelope and provided with a longitudinally extending rod-like absorption element I 6. The collector electrode is provided with electron absorption faces I'I and I8. Surrounding the electron stream between the cathode and grid and collector electrode are tubular electrodes I9 and 20, the electrode I9 being provided with a rod-like element 2l extending within and axially of the=electrode 20 for purposes to be described.

Next adjacent the electrode 20 is atubular accelerating and shielding electrode 24 coaxial with and surrounding a second inner tubular conducting element 22, which is provided with an apertured screen-like element 23 and the ends of which tubular members are closed by the ringlike apertured or screen-like element 24'. The spacings between the screen elements 23:24' and electrode absorption faces I'I and I8 of the collector electrode are of substantially the same dimensions.

The input circuit is provided by means of the resonant cavity tank circuit 25, which, may be of the concentric line type, surrounding the envelope and having gap 26 registering with thev l nant cavity.

The output resonant cavity 2l surrounds the collector end of the envelope and is provided with gap 28 registering with the gap between the electron absorption face lI8 and apertured v element 24. 'Ihe load may be taken out of the output resonant cavity by means of the loop 29.

To prevent difference of R. F. potential between the .resonant cavities and between the electrodes l2|) and 24, the resonant cavities are positioned closely adjacent each other and spaced'and insulated by means of insulating disc 25' which may be, for example, of mica. Since the tubular members 20 and 24 are closely adjacent the inner wall of the tube envelope, the large capacity coupling between these two members and the inner tubular members of the registering cavities readily by-pass the R. F. current so that there is no R. F. potential between electrodes 20 and 24 but only desired D. C. potentials.

Voltage sources for the heating current, for providing the bias which may be positive or negative for the grid I3, and the potentials for the various electrodes and resonant cavities are indicated at 30, 3l and 32.

The collar I4 on grid I3 and the tubular electrode I9 positioned closely adjacent the inner tubular member of the resonant cavity 24 are capacitively coupled with the resonant cavity and thus by-pass R. F. currents so that there is no R. F. potential between grid I3 and accelerating electrode I9.

In operation an electron beam is directed axially of the envelope through the tubular electrodes I9 and 20 and across the gap between these electrodes and the gap 2B of the resonant cavity. In this space the electrons are subjected to a radio frequency eld and the velocities of the electrons are cyclically variedand are accelerated or decelerated, depending upon the phase relationship of the electrons with respect to the radio frequency potentials across the gap. Electrons accelerated across the gap are subjected to a transverse radial electrostatic field which increases from the center outwardly, since the electrode 2| is at a lower potential than electrode 20. Thus the fast moving electrons are directed outwardly to form an advancing collar or ring of electrons around element 22 through element 24. During the next half cycle the decelerated electrons are subjected to an inwardly directed transverse radial field so that the decelerated electrons are directed toward the center or along the axis of the tube. Thus a tubular group of electrons and a rod-like group of electrons advance Within the electrode 24. The element 22 is of such length thatthetransit time of the electrons along it is equal to approximately a half-period so that the slow and fast electrons cross the gaps between screen 23 and absorption face I1, and the screen 24' and absorption face I8 at substantially the same instant or time, thus providing a pulse in the resonant cavity 21. The electrons pass across the gap when the radio frequency eld is properly phased to decelerate the electrons. To still further decelerate electrons so as to increase the energy transfer between the electrons and cavity, the electrode I5 is maintained at a. potential lower than that of the electrode 24 and the resonant cavity. Thus it is possible to absorb all of the energy from the electrons and abstract substantially all of the energy in the same manner as would be done if grouping were utilized. The

method has 'the further advantage that the mutual repulsion of the electrons is considerably reduced since the densityof the electrons is not as great.

In order to reduce the absorption period by means of my construction, the electrode 24 may be maintained at a high positive potential with respeci; to electrode 20 so that the electrons are accelerated across the gap between these two electrodes, thus both groups of electrons are made to pass across the gaps between the absorbing surfaces of the collector electrode and the assenso screen elements 23 and 24' of electrode 24 in a short period of time. This has the advantage of increasing the amplitude of the pulse generated. It is of course obvious that, if desired, the grid I3 could be utilized to rst modulate the electron stream before being directed across the gap between electrodes I9 and 20 so that the device could be utilized, for example, as a converter, if so desired, by impressing on the resonant cavity 25 the local oscillator voltage.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact form illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

l. An electron discharge device having a cath.- ode for supplying a stream of electrons, and collector electrode means for receiving said electrons, means between the cathode and collector electrode mea-ns and including a pair of electrodes spaced axiallyproviding a gap across which may be generated a. high frequency field for cyclically varying the velocity of the electrons in said stream, circuit means coupled between said pair of electrodes for applying a high frequency voltage between said pair of electrodes, said collector electrode means having electron receiving surfaces spaced at different distances from the cathode, and means for subjecting the electron stream to alternating radial electrostatic elds after the velocity of the electrons has been cyclically varied for directing electrons to different receiving surfaces to be received simultaneously by the collector electrode means, and an output circuit coupled to said collector electrode means.

2. An electron discharge device having a cathf ode for supplying a stream of electrons and a collector electrode for receiving said electrons, means between said cathode and said collector electrode for cyclically varying the `velccity of the electrons in said stream and including a pair of electrodes between the cathode and collector electrode surrounding the path of said stream and spaced axially providing a gap surrounding said electron stream path, said collector electrode having surfaces spaced at different distances from said cathode, and means adjacent said pair of electrodes for subjecting the stream of, electrons to alternating radial electrostatic fields after th velocity of the electrons has been cyclically varied for directing the electrons to different ones of said surfaces of said collector electrode whereby different velocity electrons are substantially simultaneously absorbed by said collecting electrode.

3. An electron discharge device having a cathode for supplying a stream of electrons and a collector electrode for receiving said electrons,

means for modulating said electron stream and including a resonator having a gap surrounding the path of said stream and located between the cathode and collector electrode, said collector electrode extending transversely of the path of the electron stream providing an electron receiving surface and having an vaxial extension provided with an electron receiving surface spaced closer to said cathode than the receiving surface of said collector electrode proper, and means connected to said resonator on one side of said gap and extending axially within the resonator on the other side of said gap for subjecting said stream of electrons to alternating radial fields after said stream of electrons has been modulated by said resonator to direct electrons to either the receiving surface of the axial extension or the receiving surface of the collector electrode proper.

4. An electron discharge device having an envelope containing a cathode for supplying a stream .of electrons, and a collector for receiving said electrons, a pair of tubular electrodes positioned between the cathode and the collector and spaced axially providing a gap, one of Said tubular electrodes being provided with a rodlike extension positioned within and axially of the other tubular electrode, said collector having an electron receiving surface transverse to the path of the electron stream and provided with a rod-like extension havingr an electron receiving surface closer to said cathode than the receiving surface of the collector proper, and screening and accelerating means positioned adjacent the collector and spaced therefrom providing a gap and having a tubular member surrounding said rod-like extension, and a resonator surrounding said cathode, and axially spaced tubular electrodes and having a gap registering with the gap between said pair of tubular electrodes, and an output resonatorsurrounding the screening and accelerating means and collector and having a gap registering with the gap between the screening and accelerating means and the collector.

5. An electron discharge device having an envelope containing a cathode for supplying a stream of electrons, and a collector for receiving said electrons, and means including a pair of tubular electrodes positioned between the cathode and the collector and spaced axially providing a gap for providing a high frequency electric eld through which the stream of electrons is directed for varying the velocity of the electrons cyclically, one of said electrodes being provided with a rod-like extension positioned Within and axially of the other electrode, said collector having an electron receiving surface transverse to the path of the stream of electrons and provided with an extension having an electron receiving surface closer to said cathode thanV the receiving surface of the collector proper, and screening and accelerating means positioned adjacent the collector electrode and having a portion surrounding said extension.

6. An electron discharge device having an envelope containing a cathode for supplying .a

stream of electrons, and a collector for receiving said electrons, a pair of tubular electrodes positioned between the cathode and the collector and spaced axially providing a gap, one of said electrodes being provided with a rod-like extension positioned within and axially of the other electrode, said collector having an electron receiving surface transverse to the path of the stream of electrons and provided with an extension having an electron receiving surface closer to said cathode than the receiving surface of the collector proper, and screening and accelerating means positioned adjacent but spaced from the collector and having an inner tubular member surrounding said extension, and a resonator surrounding said cathode and axially spaced tubular electrodes and having a gap registering with the gap between said tubular electrodes and an output resonator surrounding the screening and accelerating means and collector and having a. gap registering with the space between the -screening and accelerating means and said co1- charge device.

7. An electron discharge device having a cathode for supplying a stream of electrons, and a. collector for receiving said electrons, and an accelerating electrode positioned next adjacent the collector electrode, and a cavity resonator surrounding the discharge path between said cathode and collector and having a gap surrounding said electron discharge path for subjecting the electron stream to a high frequency eld between said cathode and said accelerating electrode and an output cavity resonator having a gap surrounding the electron path between said accelerating electrode and collector.

8. An electron discharge device comprising an elongated envelope having at one end a cathode for supplying electrons, and a collector at the other end of the envelope for receiving said electrons, a pair of tubular electrodes positioned between the cathode and the collector and spaced axially providing a gap surrounding the path of the stream of electrons, the tubular electrode adjacent the cathode being provided with a rodlike extension positioned within and axially of the other tubular electrode, and a screen and accelerating electrode positioned between said pair of tubular electrodes and the collector and spaced therefrom, said collector having a surface extending transversely of the tube envelope for receiving electrons and provided with an axially positioned rod-like element having an electron collecting surface positioned closer to said cathode than the transversely extending surface of the collector proper, said screen and accelerating electrode comprising a pair of coaxial'tubular members and an apertured element extending across the end of the inner tubular portion adjacent the receiving surface of the rod-like extension of the collector, and another apertured element electrically connecting the ends of the tubular members adjacent the electron receiving surface of the collector and a resonator surrounding the cathode, and having a gap registering with the gap between the pair of tubular electrodes, and an output resonator surrounding the collector and screen and accelerating electrode, and having a gap registering with the space between the screen and accelerating electrode and the collector, said Vresonators being closely adjacent each other, said other tubular electrode and said screen and accelerating electrode being closely adjacent the inner tubular wall of the envelope.

- and electrode means positioned between the cathode and collector for cyclically varying the velocity of the electrons and electrode means for subjecting the electrons to altern-ating radial fields for causing a. radial and axial spacing of the electrons into groups. said collector electrode having surfaces at different distances from said cathode for simultaneously abstracting energy from a plurality of groups of electrons.

10. An electron discharge device having a cathode for supplying a stream of electrons and a collector for receiving said stream of electrons, and a rst electrode means positioned between the cathode and collector for cyclically varying the velocity of the electrons and second electrode means for subjecting the electrons to alternating radial elds for causing a radial and axial spacing of the electrons into groups, said collector electrode having surfaces at diierent distances from said cathode for simultaneously abstracting energy from a plurality of groups of electrons. and means positioned between the :electrode means and collector for accelerating electrons toward said collector.

11. An electron discharge device having a cathode for supplying a stream of electrons and a I collector for receiving said stream of electrons,

and a rst electrode means including spaced electrodes positioned between the cathode and collector for cyclically varying the velocity of the electrons and a second electrode means for subjecting the electrons to alternating radial fields for causing a radial and axial spacing of the electrons into groups, said collector having surfaces at diierent distances from said cathode for simultaneously abstracting energy from a plurality of groups of electrons, and a third electrode means positioned between the rst electrode means and collector for accelerating electrons toward said collector.

12. An electron discharge device having an envelope containing a cathode for supplying a stream of electrons and a collector for receiving said electrons, and an accelerating electrode next adjacent said collector electrode and spaced therefrom, a resonator surrounding said envelope and provided with a gap surrounding the discharge path between the cathode and accelerating electrode, and a second resonator surrounding said envelope and having a gap registering with the space between the accelerating electrode and said collector.

13. An electron discharge device having an en velope containing a cathode for supplying a stream of electrons, anda collector for receiving said electrons, a pair of tubular electrodes positioned between the cathode and collector and spaced axially to provide a high frequency eld therebetween to which said stream of electrons is subjected, and screening and accelerating means positioned. adjacent the collector land spaced therefrom to provide a second high frequency field through which said stream of electrons is projected for extracting energy from said electrons, a rst resonator coupled to said pair of tubular electrodes, and a second resonator coupled to the screening and accelerating means and said collector.

14. An electron discharge device having a cathode for supplying a stream of electrons. and a collector for receiving said electrons, a resonator surrounding the path of the stream of electrons and having a gap lying in a plane transverse to the path of the stream between the cathode and collector, a rod-like conductor connected to said resonator on one side of said gap and extending within and axially of the resonator on the other side of said gap, said collector having an electron receiving surface transverse to the path of the electron stream and provided with an extension having an electron receiving surface closer to said cathode than the receiving surface of the collector proper, and screening and accelerating means positioned adjacent the collector and spaced therefrom and having a tubular member surrounding said extension, and an output resonator surrounding the discharge path and having a gap surrounding the discharge path and registering with the space between the screening and accelerating means and said collector.

WILLIAM A. ZALESAK. 

